So lets start, my friends.
Today i couldn't log on to one server running Windows 2008 R2. Got this error message:

Remote Desktop cannot verify the identity of the remote computer because there is a time or date difference between your computer and the remote computer

Spent few hours struggling against this problem. connected to problematic server with PSexec, Verified date\time\time zone, tried to resync time with Domain controller. Everything went just OK, no error messages, nothing.
Then I compared every single sing of problematic machine with neighboring server. Afterall I noticed IPv6 Enabled on server where I tried to log on. After disabling IPv6 i got it working!

Solution: Disable IPv6 on target server 

Still not fixed...

Solution: Well, the solution is not that interesting for posting it here, but, such as I've already started this article...: server's uptime was 500+ days and all we need to do to fix this strange behavior was a magic restart.